The invention relates to the pumping of viscous materials such as plaster, slurry, and fireproofing materials. Particularly, the invention relates to improvements in pumps of this type which allow for higher production, particularly in the pumping of fireproofing materials such as Monokote spray applied fireproofing material manufactured by the W. R. Grace, Company which is a cementitious (plaster) material requiring only the addition of water on the job. Typically, such materials include ninety to ninety-six percent Gypsum binder and aggregate with fiberglass, fillers, and air entraining agents in small amounts. These materials are highly spongy in a pumping state undergoing pumping. Due to the spongy nature of the material, it is difficult, if not impossible, to pump all of the material out of the pump chamber. Some of the material must be used to compress the material that is pumped, all of which cause the prior pumps utilized to pump such viscous materials rather ineffecient.
Most of the pumps utilized to pump the viscous fireproofing materials are plaster type pumps which were developed to pump a more stable compressible material. These pumps are not very efficient for pumping light weight, spongy materials which are normally used as fireproofing materials. In particular, a problem of dead air spaces exist in the use of plaster type pumps for pumping spongy fireproofing material. On the suction stroke, a blow by of air may occur past the piston assembly which creates an air pocket on the compression chamber side of the piston, all of which reduce the volume of material pumped.
In particular, the invention is directed to improvements in a model TM 30 plaster pump manufactured by the Essick Manufacturing Company of Los Angeles, Calif. and to increasing the production of this pump when used for pumping viscous fireproofing materials, particularly of a spongy nature.
Other typical plaster pumps and pumps for viscous materials are disclosed in U.S. Pat. Nos. 4,521,163; 2,432,671; and 2,146,709.
Accordingly, an object of the invention is to increase the efficiency and production of a plaster pump for pumping spongy fireproofing materials and the like.
Another object of the invention is to provide improvements to a pump for viscous material in which the suction and compression strokes are increased in their capacity.
Another object of the invention is to provide improvements which allow for pumping of soft, spongy fireproofing materials in plaster type pumps with increased production by eliminating restrictive passages and increasing the suction and compression capacities of the pump.
Another object of the present invention is to provide an improved piston assembly for a pump for pumping viscous materials which improves the sealing between the piston assembly and the piston cylinder wall as well as increasing the compression, wear, resistance, and pumping efficiency of the piston assembly.
Yet another object of the invention is to provide an improved pump for pumping viscous materials in which the need for down time of the pump is considerably reduced.